1. Field of the Invention
The present invention relates generally to the transfer of fireplace-generated heat to the surrounding ambient air outside of the fireplace and, more particularly, is concerned with a fireplace heat transfer apparatus positioned outside of the fire chamber across the fireplace entrance and which is adjustable for regulating the rate of heat transfer by adjusting thermosiphon flow of heated air within the apparatus.
2. Description of the Prior Art
Heretofore there have been many different devices proposed for transferring the heat generated by a fireplace to the surrounding ambient air in the room or area containing the fireplace. Representative examples of prior art fireplace heat transfer apparatus include those shown in U.S. Pat. Nos. 2,747,568; 3,368,545; 4,282,855; 4,290,409 and British Specification No. 808,053.
As pointed out in U.S. Pat. No. 4,282,855 to Perry, for purposes of energy conservation it is important that fireplace heat transfer apparatus conserve energy both during periods of use and nonuse. Perry discloses a fireplace screen system which uses an air blower assembly to communicate with the interior space or chamber between a pair of vertical, spaced apart glass panels for circulating air heated by the fireplace into the surrounding room area. Perry asserts that the construction of the disclosed screen system serves the desired dual conservation purposes: it provides a heat barrier and insulation barrier when the fireplace is not in use and provides a heat transfer structure when the fireplace is in use. However, it is apparent that Perry's system embodies certain potential shortcomings from the standpoint of energy conservation for it contemplates use of an energy-consuming blower to force ambient air into the fireplace and up through the chamber formed between the glass panels.
Consequently, a need still exists for a fireplace heat transfer apparatus which achieves energy conservation during periods of both use and nonuse of the fireplace and which does so in a simple, reliable manner not itself requiring the use of energy.